Liquid crystal composition and liquid crystal display device

ABSTRACT

Disclosed are: a liquid crystal composition which satisfies at least one property selected from a high upper limit temperature in a nematic phase, a low lower limit temperature in a nematic phase, a low viscosity, high optical anisotropy, high dielectric anisotropy, a high specific resistance, high stability against ultraviolet ray, high stability against heat and the like or has a proper balance between at least two properties selected from the above-mentioned properties; and an AM element having a short response time, a high voltage holding ratio, a high contrast ratio, a long service life and the like. Specifically disclosed are: a liquid crystal composition which comprises a specific pentacyclic compound having high optical anisotropy and high dielectric anisotropy as the first component, a specific compound having a low viscosity as the second component, and a specific tetracyclic compound having a high upper limit temperature as the third component, and which shows a nematic phase; and a liquid crystal display element comprising the composition.

TECHNICAL FIELD

The invention relates mainly to a liquid crystal composition suitablefor use in an active matrix (AM) device, and an AM device containing thecomposition. The invention relates particularly to a liquid crystalcomposition having a positive dielectric anisotropy, and to a device ofa twisted nematic (TN) mode, an optically compensated bend (OCB) mode,an in-plane switching (IPS) mode or a polymer sustained alignment (PSA)mode containing the composition.

BACKGROUND ART

In a liquid crystal display device, a classification based on theoperation mode of liquid crystals includes phase change (PC), twistednematic (TN), super twisted nematic (STN), electrically controlledbirefringence (ECB), optically compensated bend (OCB), in-planeswitching (IPS), vertical alignment (VA), polymer sustained alignment(PSA), and so forth. A classification based on a driving mode includes apassive matrix (PM) and an active matrix (AM). The PM is furtherclassified into static, multiplex and so forth, and the AM is furtherclassified into a thin film transistor (TFT), a metal-insulator-metal(MIM) and so forth. The TFT is further classified into amorphous siliconand polycrystal silicon. The latter is classified into ahigh-temperature type and a low-temperature type according to aproduction process. A classification based on a light source includes areflection type utilizing natural light, a transmission type utilizing abacklight, and a semi-transmission type utilizing both the natural lightand the backlight.

These devices contain a liquid crystal composition having suitablecharacteristics. The liquid crystal composition has a nematic phase.General characteristics of the composition should be improved to obtainan AM device having good general characteristics. Table 1 belowsummarizes a relationship between the general characteristics of thetwo. The general characteristics of the composition will be explainedfurther based on a commercially available AM device. A temperature rangeof a nematic phase relates to a temperature range in which the devicecan be used. A desirable maximum temperature of the nematic phase is 70°C. or more and a desirable minimum temperature is −10° C. or less. Theviscosity of the composition relates to the response time of the device.A short response time is desirable for displaying moving images with thedevice. Accordingly, a small viscosity of the composition is desirable.A small viscosity at a low temperature is more desirable.

TABLE 1 General Characteristics of Liquid Crystal Composition and AMDevice General Characteristics of General Characteristics of an AM No. aComposition Device 1 Temperature range of a Usable temperature range iswide nematic phase is wide 2 Viscosity is small¹⁾ Response time is short3 Optical anisotropy is Contrast ratio is large suitable 4 Dielectricanisotropy is Threshold voltage is low and positively or negativelyelectric power consumption is large small Contrast ratio is large 5Specific resistance is Voltage holding ratio is large and large acontrast ratio is large 6 It is stable to ultraviolet Service life islong light and heat ¹⁾A liquid crystal composition can be injected intoa cell in a short time.

The optical anisotropy of the composition relates to the contrast ratioof the device. The product (Δn×d) of the optical anisotropy (Δn) of thecomposition and the cell gap (d) of the device is designed in order tomaximize the contrast ratio. A suitable value of the product depends onthe kind of operation modes. In a device having a TN mode or the like, asuitable value is 0.45 μm. In this case, a composition having a largeoptical anisotropy is desirable for a device having a small cell gap. Alarge dielectric anisotropy of the composition contributes to a lowthreshold voltage, a small electric power consumption and a largecontrast ratio. Accordingly, a large dielectric anisotropy is desirable.A large specific resistance of the composition contributes to a largevoltage holding ratio and a large contrast ratio of the device.Accordingly, a composition having a large specific resistance isdesirable at room temperature and also at a high temperature in theinitial stage. A composition having a large specific resistance isdesirable at room temperature and also at a high temperature after ithas been used for a long time. The stability of the composition toultraviolet light and heat relates to the service life of the liquidcrystal display device. In the case where the stability is high, thedevice has a long service life. These characteristics are desirable foran AM device used in a liquid crystal projector, a liquid crystaltelevision and so forth.

A composition having a positive dielectric anisotropy is used for an AMdevice having a TN mode. On the other hand, a composition having anegative dielectric anisotropy is used for an AM device having a VAmode. A composition having a positive or negative dielectric anisotropyis used for an AM device having an IPS mode. A composition having apositive or negative dielectric anisotropy is used for an AM devicehaving a PSA mode. Examples of the liquid crystal composition having apositive dielectric anisotropy are disclosed in the following patentdocuments.

-   [Patent Document 1] DE 4006921-   [Patent Document 2] WO 1996/011897-   [Patent Document 3] JP 2003-176251-   [Patent Document 4] WO 2005/019377

A desirable AM device is characterized as having a usable temperaturerange that is wide, response time that is short, a contrast ratio thatis large, threshold voltage that is low, a voltage holding ratio that islarge, a service life that is long, and so forth. Even one millisecondshorter response time is desirable. Thus, a composition havingcharacteristics such as a high maximum temperature of a nematic phase, alow minimum temperature of a nematic phase, a small viscosity, a largeoptical anisotropy, a large dielectric anisotropy, a large specificresistance, a high stability to ultraviolet light, a high stability toheat, and so forth is especially desirable.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

An object of the invention is to provide a liquid crystal compositionthat satisfies many characteristics among the characteristics such as ahigh maximum temperature of a nematic phase, a low minimum temperatureof a nematic phase, a small viscosity, a large optical anisotropy, alarge dielectric anisotropy, a large specific resistance, a highstability to ultraviolet light and a high stability to heat. Anotherobject of the invention is to provide a liquid crystal composition thatis properly balanced regarding many characteristics. Still anotherobject of the invention is to provide a liquid crystal display devicethat contains the liquid crystal composition. A further object of theinvention is to provide a liquid crystal composition that has a largeoptical anisotropy, a large dielectric anisotropy, a high stability toultraviolet light and so forth, and is to provide an AM device that hasa short response time, a large voltage holding ratio, a large contrastratio, a long service life and so forth.

Means for Solving the Problems

The invention concerns a liquid crystal composition having a nematicphase that includes three components, wherein the first component is atleast one compound selected from the group of compounds represented byformulas (1-1) and (1-2), the second component is at least one compoundselected from the group of compounds represented by formula (2), and thethird component is at least one compound selected from the group ofcompounds represented by formula (3):

wherein R¹ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons or alkenyl having 2 to 12 carbons; R² and R³ are eachindependently alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12carbons in which arbitrary hydrogen is replaced by fluorine; ring A,ring B, ring C and ring D are each independently 1,4-cyclohexylene,1,4-phenylene, 2-fluoro-1,4-phenylene, or 3-fluoro-1,4-phenylene, or2,5-difluoro-1,4-phenylene; Z¹, Z² and Z³ are each independently asingle bond, ethylene, carbonyloxy, or difluoromethyleneoxy; at leastone of Z¹, Z² and Z³ is difluoromethyleneoxy; Z⁴, Z⁵ and Z⁶ are eachindependently a single bond, ethylene, or carbonyloxy; X¹, X², X³, X⁴,X⁵, X⁶, X⁷ and X⁸ are each independently hydrogen or fluorine; Y¹ isfluorine, chlorine or trifluoromethoxy; and m is 0 or 1.

Advantages of the Invention

One of the advantages of the invention is to provide a liquid crystalcomposition that satisfies many characteristics among thecharacteristics such as a high maximum temperature of a nematic phase, alow minimum temperature of a nematic phase, a small viscosity, a largeoptical anisotropy, a large dielectric anisotropy, a large specificresistance, a high stability to ultraviolet light and a high stabilityto heat. Another of the advantages of the invention is to provide aliquid crystal composition that is properly balanced regarding manycharacteristics. Another of the advantages of the invention is toprovide a liquid crystal display device that contains the liquid crystalcomposition. One aspect of the invention is to provide a liquid crystalcomposition that has a large optical anisotropy, a large dielectricanisotropy, a high stability to ultraviolet light and so forth, and isto provide an AM device that has a short response time, a large voltageholding ratio, a large contrast ratio, a long service life and so forth.

BEST MODE FOR CARRYING OUT THE INVENTION

The terms used in the specification and claims are defined as follows.The liquid crystal composition or the liquid crystal display device ofthe invention may occasionally be expressed simply as “the composition”or “the device,” respectively. A liquid crystal display device is ageneric term for a liquid crystal display panel and a liquid crystaldisplay module. The “liquid crystal compound” is a generic term for acompound having a liquid crystal phase such as a nematic phase and asmectic phase, and also for a compound having no liquid crystal phasebut being useful as a component of a composition. The useful compoundcontains a 6-membered ring such as 1,4-cyclohexylene and 1,4-phenylene,and its molecular structure is rod-like. An optically active compound ora polymerizable compound may occasionally be added to the composition.Even in the case where the compound is a liquid crystal compound, thecompound is classified into an additive herein. At least one compoundselected from the group of compounds represented by formula (1-1) may beabbreviated to “the compound (1-1).” “The compound (1-1)” means onecompound or two or more compounds represented by formula (1-1). Theother formulas are applied with the same rules. The term “arbitrary”indicates that both the position and the number are arbitrary, excludingthe case where the number is 0.

A higher limit of a temperature range of a nematic phase may beabbreviated to “a maximum temperature.” A lower limit of a temperaturerange of a nematic phase may be abbreviated to “a minimum temperature.”“A specific resistance is large” means that the composition has a largespecific resistance at room temperature and also at a high temperaturein the initial stage, and that the composition has a large specificresistance at room temperature and also at a high temperature even afterit has been used for a long time. “A voltage holding ratio is large”means that a device has a large voltage holding ratio at roomtemperature and also at a high temperature in the initial stage, andthat the device has a large voltage holding ratio at room temperatureand also at a high temperature even after it has been used for a longtime. In the description of the characteristics such as the opticalanisotropy, measured values obtained by the methods disclosed inExamples are used. The first component is one compound or two or morecompounds. “A ratio of the first component” means the percentage byweight (% by weight) based on the total weight of a liquid crystalcomposition. A ratio of the second component and so forth are appliedwith the same rule. A ratio of an additive mixed with the compositionmeans the percentage by weight (% by weight) based on the total weightof a liquid crystal composition.

The symbol R¹ was used for a plurality of compounds in the chemicalformulas for component compounds. In these compounds, two arbitrary R¹maybe identical or different. In one case, for example, R¹ of thecompound (1-1) is ethyl and R^(l) of the compound (1-2) is ethyl. Inanother case, R¹ of the compound (1-1) is ethyl and R¹ of the compound(1-2) is propyl. The same rule applies to R², R³, and so forth. “CL” inthe chemical formulas represents chlorine.

The invention has the following features:

Item 1. The invention concerns a liquid crystal composition having anematic phase that includes three components, wherein the firstcomponent is at least one compound selected from the group of compoundsrepresented by formulas (1-1) and (1-2), the second component is atleast one compound selected from the group of compounds represented byformula (2), and the third component is at least one compound selectedfrom the group of compounds represented by formula (3):

wherein R¹ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons or alkenyl having 2 to 12 carbons; R² and R³ are eachindependently alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12carbons in which arbitrary hydrogen is replaced by fluorine; ring A,ring B, ring C and ring D are each independently 1,4-cyclohexylene,1,4-phenylene, 2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene, or2,5-difluoro-1,4-phenylene; Z¹, Z² and Z³ are each independently asingle bond, ethylene, carbonyloxy or difluoromethyleneoxy; at least oneof Z¹, Z² and Z³ is difluoromethyleneoxy; Z⁴, Z⁵ and Z⁶ are eachindependently a single bond, ethylene or carbonyloxy; X¹, X², X³, X⁴,X⁵, X⁶, X⁷ and X⁸ are each independently hydrogen or fluorine; Y¹ isfluorine, chlorine or trifluoromethoxy; and m is 0 or 1.

Item 2. The liquid crystal composition according to item 1, wherein thefirst component is at least one compound selected from the group ofcompounds represented by formulas (1-1-1) to (1-1-3), (1-2-1) and(1-2-2).

Wherein R¹ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons or alkenyl having 2 to 12 carbons; X¹, X², X³, X⁴, X⁵, X⁶, X⁷,and X⁸ are each independently hydrogen or fluorine; and Y¹ is fluorine,chlorine or trifluoromethoxy.

Item 3. The liquid crystal composition according to item 2, wherein thefirst component is at least one compound selected from the group ofcompounds represented by formulas (1-1-1) and (1-2-2).

Item 4. The liquid crystal composition according to any one of items 1to 3, wherein the second component is at least one compound selectedfrom the group of compounds represented by formulas (2-1) to (2-6).

Wherein R² and R³ are each independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, oralkenyl having 2 to 12 carbons in which arbitrary hydrogen is replacedby fluorine.

Item 5. The liquid crystal composition according to item 4, wherein thesecond component is at least one compound selected from the group ofcompounds represented by formula (2-1).

Item 6. The liquid crystal composition according to item 4, wherein thesecond component is at least one compound selected from the group ofcompounds represented by formula (2-6).

Item 7. The liquid crystal composition according to item 4, wherein thesecond component is a mixture of at least one compound selected from thegroup of compounds represented by formula (2-1), and at least onecompound selected from the group of compounds represented by formula(2-4).

Item 8. The liquid crystal composition according to item 4, wherein thesecond component is a mixture of at least one compound selected from thegroup of compounds represented by formula (2-1), and at least onecompound selected from the group of compounds represented by formula(2-6).

Item 9. The liquid crystal composition according to item 4, wherein thesecond component is a mixture of at least one compound selected from thegroup of compounds represented by formula (2-1), at least one compoundselected from the group of compounds represented by formula (2-4), andat least one compound selected from the group of compounds representedby formula (2-6).

Item 10. The liquid crystal composition according to any one of items 1to 9, wherein the third component is at least one compound selected fromthe group of compounds represented by formulas (3-1) to (3-4).

Wherein R² and R³ are each independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, oralkenyl having 2 to 12 carbons in which arbitrary hydrogen is replacedby fluorine.

Item 11. The liquid crystal composition according to item 10, whereinthe third component is at least one compound selected from the group ofcompounds represented by formula (3-4).

Item 12. The liquid crystal composition according to any one of items 1to 11, wherein the ratio of the first component is in the range of 5% to25% by weight, the ratio of the second component is in the range of 30%to 80% by weight, and the ratio of the third component is in the rangeof 5% to 25% by weight, based on the total weight of the liquid crystalcomposition.

Item 13. The liquid crystal composition according to any one of items 1to 12, wherein the composition further includes at least one compoundselected from the group of compounds represented by formula (4) as thefourth component.

Wherein R¹ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons or alkenyl having 2 to 12 carbons; ring E is independently1,4-cyclohexylene, 1,3-dioxane-2,5-diyl, 1,4-phenylene,3-fluoro-1,4-phenylene, 3,5-difluoro-1,4-phenylene, or 2,5-pyrimidine;Z¹ is independently a single bond, ethylene, carbonyloxy, ordifluoromethyleneoxy; X¹ and X² are each independently hydrogen orfluorine; Y¹ is fluorine, chlorine or trifluoromethoxy; and n is 1, 2 or3.

Item 14. The liquid crystal composition according to item 13, whereinthe fourth component is at least one compound selected from the group ofcompounds represented by formulas (4-1) to (4-17).

Wherein R⁴ is alkyl having 1 to 12 carbons, or alkenyl having 2 to 12carbons.

Item 15. The liquid crystal composition according to item 14, whereinthe fourth component is at least one compound selected from the group ofcompounds represented by formula (4-9).

Item 16. The liquid crystal composition according to item 14, whereinthe fourth component is at least one compound selected from the group ofcompounds represented by formula (4-10).

Item 17. The liquid crystal composition according to item 14, whereinthe fourth component is at least one compound selected from the group ofcompounds represented by formula (4-11).

Item 18. The liquid crystal composition according to item 14, whereinthe fourth component is at least one compound selected from the group ofcompounds represented by formula (4-17).

Item 19. The liquid crystal composition according to item 14, whereinthe fourth component is a mixture of at least one compound selected fromthe group of compounds represented by formula (4-6) and at least onecompound selected from the group of compounds represented by formula(4-11).

Item 20. The liquid crystal composition according to item 14, whereinthe fourth component is a mixture of at least one compound selected fromthe group of compounds represented by formula (4-9) and at least onecompound selected from the group of compounds represented by formula(4-11).

Item 21. The liquid crystal composition according to item 14, whereinthe fourth component is a mixture of at least one compound selected fromthe group of compounds represented by formula (4-11) and at least onecompound selected from the group of compounds represented by formula(4-17).

Item 22. The liquid crystal composition according to any one of items 13to 21, wherein the ratio of the first component is in the range of 5% to25% by weight, the ratio of the second component is in the range of 30%to 80% by weight, and the ratio of the third component is in the rangeof 5% to 25% by weight, and the ratio of the fourth component is in therange of 5% to 45%, based on the total weight of the liquid crystalcomposition.

Item 23. The liquid crystal composition according to any one of items 1to 22, wherein the composition has a maximum temperature of a nematicphase of 70° C. or more, an optical anisotropy (25° C.) at a wavelengthof 589 nm of 0.08 or more, and a dielectric anisotropy (25° C.) at afrequency of 1 kHz of 2 or more.

Item 24. A liquid crystal display device contains the liquid crystalcomposition according to any one of items 1 to 23.

Item 25. The liquid crystal display device according to item 24, whereinthe operation mode of the liquid crystal display device is a twistednematic (TN) mode, an optically compensated bend (OCB) mode, or anin-plane switching (IPS) mode, and the driving mode of the liquidcrystal display device is an active matrix mode.

Item 26. The liquid crystal display device according to item 24, whereinthe operation mode of the liquid crystal display device is a polymersustained alignment (PSA) mode, and the driving mode of the liquidcrystal display device is an active matrix mode.

The invention further includes: (1) the composition described above,wherein the composition further contains an optically active compound;(2) the composition described above, wherein the composition furthercontains an additive, such as an antioxidant, an ultraviolet lightabsorbent, an antifoaming agent, a polymerizable compound, and/or apolymerization initiator; (3) an AM device containing the compositiondescribed above; (4) a device having a TN, ECB, OCB, IPS, or PSA,containing the composition described above; (5) a device of atransmission type, containing the composition described above; (6) useof the composition described above as a composition having a nematicphase; and (7) use as an optically active composition by adding anoptically active compound to the composition described above.

The composition of the invention will be explained in the followingorder. First, the constitution of component compounds in the compositionwill be explained. Second, the main characteristics of the componentcompounds and the main effects of the compounds on the composition willbe explained. Third, the combinations of the components in thecomposition, a desirable ratio of the component compounds, and the basisthereof will be explained. Fourth, a desirable embodiment of thecomponent compounds will be explained. Fifth, examples of the componentcompounds will be shown. Sixth, additives that may be added to thecomposition will be explained. Seventh, the methods for preparing thecomponent compounds will be explained. Lastly, use of the compositionwill be explained.

First, the constitution of component compounds in the composition willbe explained. The composition of the invention is classified into acomposition A and a composition B. The composition A may further containother liquid crystal compounds, an additive, an impurity, and so forth.“The other liquid crystal compounds” are different from the compound(1-1), the compound (1-2), the compound (2), the compound (3), and thecompound (4). Such compounds are mixed with the composition for thepurpose of adjusting the characteristics of the composition. The otherliquid crystal compounds desirably contain a smaller amount of a cyanocompound from the viewpoint of stability to heat or ultraviolet light. Amore desirable ratio of the cyano compound is 0% by weight. The additiveincludes an optically active compound, an antioxidant, an ultravioletlight absorbent, a coloring matter, an antifoaming agent, apolymerizable compound, a polymerization initiator and so forth. Theimpurity is a compound and so forth contaminated in a process such asthe synthesis of a component compound and so forth. Even in the casewhere the compound is a liquid crystal compound, it is classified intoan impurity.

The composition B is essentially consisting of compounds selected fromthe compound (1-1), the compound (1-2), the compound (2), the compound(3), and the compound (4). The term.“essentially” means that thecomposition does not contain a liquid crystal compound different fromthese compounds. The composition B has fewer components as compared tothe composition A. The composition B is more desirable than thecomposition A from the viewpoint of cost reduction. The composition A ismore desirable than the composition B from the viewpoint that physicalproperties can be adjusted further by adding the other liquid crystalcompounds.

Second, the main characteristics of the component compounds and the maineffects of the compounds on the composition will be explained. The maincharacteristics of the component compounds are summarized in Table 2. InTable 2, the symbol L represents large or high, the symbol M representsa middle degree, and the symbol S represents small or low. The symbolsL, M and S are classifications based on qualitative comparison among thecomponent compounds.

TABLE 2 Characteristics of Compounds Compound (1-1) (1-2) (2) (3) (4)Maximum Temperature M M S-M L S-M Viscosity L L S-M M-L M-L OpticalAnisotropy L M-L S-L M-L M-L Dielectric Anisotropy M-L M-L 0 0 S-LSpecific Resistance L L L L L

The main effects of the component compounds on the characteristics ofthe composition upon mixing the component compounds with the compositionare as follows. The compound (1-1) and the compound (1-2) increase theoptical anisotropy and increase the dielectric anisotropy. The compound(2) increases the maximum temperature or decreases the viscosity. Thecompound (3) increases the maximum temperature. The compound (4)decreases the minimum temperature and increases the dielectricanisotropy.

Third, the combinations of the components in the composition, desirableratios of the component compounds, and the basis thereof will beexplained. The combinations of the components in the composition arefirst component+second component+third component, and firstcomponent+second component+third component+fourth component.

A desirable ratio of the first component is 5% by weight or more forincreasing the optical anisotropy, and is 25% by weight or less fordecreasing the minimum temperature. A more desirable ratio is in therange from 5% to 20% by weight. A particularly desirable ratio is in therange from 5% to 15% by weight.

A desirable ratio of the second component is 30% by weight or more fordecreasing the viscosity, and is 80% by weight or less for increasingthe dielectric anisotropy. A more desirable ratio is in the range from35% to 75% by weight. A particularly desirable ratio is in the rangefrom 40% to 70% by weight.

A desirable ratio of the third component is 5% by weight or more forincreasing the maximum temperature, and is 25% by weight or less fordecreasing the minimum temperature. A more desirable ratio is in therange from 5% to 20% by weight. A particularly desirable ratio is in therange from 5% to 15% by weight.

The fourth component is suitable for preparing a composition having aparticularly large dielectric anisotropy. A desirable ratio of thecomponent is in the range from 5% to 45% by weight. A more desirableratio is in the range from 10% to 40% by weight. A particularlydesirable ratio is in the range from 15% to 35% by weight.

Fourth, a desirable embodiment of the component compounds will beexplained. R¹ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons or alkenyl having 2 to 12 carbons. Desirable R¹ is alkyl having1 to 12 carbons for increasing the stability to ultraviolet light orheat. R² and R³ are each independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, oralkenyl having 2 to 12 carbons in which arbitrary hydrogen is replacedby fluorine. Desirable R² is alkenyl having 2 to 12 carbons fordecreasing the minimum temperature or decreasing the viscosity.Desirable R³ is alkyl having 1 to 12 carbons for increasing thestability to ultraviolet light or heat. R⁴ is alkyl having 1 to 12carbons or alkenyl having 2 to 12 carbons. Desirable R⁴ is alkyl having1 to 12 carbons for increasing the stability to ultraviolet light orheat.

Desirable alkyl is methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl,or octyl. More desirable alkyl is ethyl, propyl, butyl, pentyl, orheptyl for decreasing the viscosity.

Desirable alkoxy is methoxy, ethoxy, propoxy, butoxy, pentyloxy,hexyloxy, or heptyloxy. More desirable alkoxy is methoxy or ethoxy fordecreasing the viscosity.

Desirable alkenyl is vinyl, 1-propenyl, 2-propenyl, 1-butenyl,2-butenyl, 3-butenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl,1-hexenyl, 2-hexenyl, 3-hexenyl, 4-hexenyl, or 5-hexenyl. More desirablealkenyl is vinyl, 1-propenyl, 3-butenyl, or 3-pentenyl for decreasingthe viscosity. A desirable configuration of —CH═CH— in these alkenylsdepends on the position of a double bond. Trans is desirable in thealkenyl such as 1-propenyl, 1-butenyl, 1-pentenyl, 1-hexenyl,3-pentenyl, and 3-hexenyl for decreasing the viscosity. Cis is desirablein the alkenyl such as 2-butenyl, 2-pentenyl and 2-hexenyl. In thesealkenyls, linear alkenyl is preferable to branched alkenyl.

Desirable examples of alkenyl in which arbitrary hydrogen is replaced byfluorine are 2,2-difluorovinyl, 3,3-difluoro-2-propenyl,4,4-difluoro-3-butenyl, 5,5-difluoro-4-pentenyl, and6,6-difluoro-5-hexenyl. More desirable examples are 2,2-difluorovinyland 4,4-difluoro-3-butenyl for decreasing the viscosity.

Ring A, ring B, ring C and ring D are each independently1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene,3-fluoro-1,4-phenylene, or 2,5-difluoro-1,4-phenylene. Desirable ring A,ring B and ring C are 1, 4-cyclohexylene for decreasing the viscosity,or 1,4-phenylene for increasing the optical anisotropy. Desirable ring Dis 3-fluoro-1,4-phenylene for decreasing the minimum temperature. Ring Eis 1,4-cyclohexylene, 1,3-dioxan-2,5-diyl, 1,4-phenylene,3-fluoro-1,4-phenylene, 2,5-difluoro-1,4-phenylene, or 2,5-pyrimidine.When n is 2 or 3, two arbitrary rings E may be the same or different.Desirable ring E is 1,4-phenylene for increasing the optical anisotropy.

Z¹, Z² and Z³ are each independently a single bond, ethylene,carbonyloxy or difluoromethyleneoxy. When n is 2 or 3, two arbitrary Z¹may be the same or different. Desirable Z¹, Z² and Z³ are eachindependently difluoromethyleneoxy for increasing the dielectricanisotropy. Z⁴, Z⁵ and Z⁶ are each independently a single bond,ethylene, or carbonyloxy. Desirable Z⁴, Z⁵ and Z⁶ are each independentlya single bond for decreasing the viscosity.

X¹, X², X³, X⁴, X⁵, X⁶, X⁷, and X⁸ are each independently hydrogen orfluorine. Five or more of X¹, X², X³, X⁴, X⁵, X⁶, X⁷, and X⁸ aredesirably fluorine for increasing the dielectric anisotropy.

Y¹ is fluorine, chlorine or trifluoromethoxy. Desirable Y¹ is fluorinefor decreasing the minimum temperature.

Fifth, examples of the component compounds will be shown. In thedesirable compounds described below, R⁵ is linear alkyl having 1 to 12carbons. R⁶ is linear alkyl having 1 to 12 carbons or linear alkoxyhaving 1 to 12 carbons. R⁷ and R⁸ are each independently linear alkylhaving 1 to 12 carbons or linear alkenyl having 2 to 12 carbons. On theconfiguration of 1,4-cyclohexylene, trans is preferable to cis forincreasing the maximum temperature.

Desirable compound (1-1) are the compounds (1-1-1-1) to (1-1-1-3), thecompounds (1-1-2-1) to (1-1-2-2), and the compound (1-1-3-1). Moredesirable compound (1-1) are the compounds (1-1-1-1) to (1-1-1-3).Especially desirable compound (1-1) are the compound (1-1-1-1).Desirable compound (1-2) are the compounds (1-2-1-1) and (1-2-2-1).Desirable compound (2) are the compounds (2-1-1) to (2-6-1). Moredesirable compound (2) are the compound (2-1-1), the compound (2-3-1),the compound (2-4-1), and the compound (2-6-1). Especially desirablecompound (2) are the compound (2-1-1), the compound (2-4-1) and thecompound (2-6-1). Desirable compound (3) are the compounds (3-1-1) to(3-4-1). More desirable compound (3) are the compound (3-4-1). Desirablecompound (4) are the compounds (4-1-1) to (4-23). More desirablecompound (4) are the compound (4-9-1), the compound (4-11-1), thecompound (4-15-1) and the compound (4-17-1). Especially desirablecompound (4) is the compound (4-11-1) and the compound (4-17-1).

Sixth, additives capable of being mixed with the composition will beexplained. The additives include an optically active compound, anantioxidant, an ultraviolet light absorbent, a coloring matter, anantifoaming agent, a polymerizable compound, a polymerization initiatorand so forth. An optically active compound is mixed in the compositionfor inducing the helical structure of liquid crystals to provide a twistangle. Examples of the optically active compound include the compounds(5-1) to (5-4) below. A desirable ratio of the optically active compoundis 5% by weight or less. A more desirable ratio is in the range from0.01% to 2% by weight.

An antioxidant is mixed with the composition in order to avoid adecrease in specific resistance caused by heating in the air, or tomaintain a large voltage holding ratio at room temperature and also at ahigh temperature even after the device has been used for a long time.

Preferred examples of the antioxidant include the compound (6), whereinn is an integer of from 1 to 9. In the compound (6), desirable n are 1,3, 5, 7, or 9. More desirable n is 1 or 7. When n is 1, the compound (6)has a large volatility, and is effective in preventing the decrease ofspecific resistance caused by heating in the air. When n is 7, thecompound (6) has a small volatility, and is effective in maintaining alarge voltage holding ratio at room temperature and also at a hightemperature even after the device has been used for a long time. Adesirable ratio of the antioxidant is 50 ppm or more for obtaining theadvantage thereof, and is 600 ppm or less for preventing the maximumtemperature from being decreased and preventing the minimum temperaturefrom being increased. A more desirable ratio thereof is in the rangefrom 100 ppm to 300 ppm.

Preferred examples of the ultraviolet light absorbent include abenzophenone derivative, a benzoate derivative and a triazolederivative. A light stabilizer such as amine with steric hindrance isalso desirable. A desirable ratio of the absorbent or stabilizer is 50ppm or more for obtaining the advantage thereof, and is 10,000 ppm orless for preventing the maximum temperature from being decreased andpreventing the minimum temperature from being increased. A moredesirable ratio thereof is in the range from 100 ppm to 10,000 ppm.

A dichroic dye such as an azo dye or an anthraquinone dye is mixed withthe composition to suit for a device of a guest host (GH) mode. Adesirable ratio of the dye is in the range from 0.01% to 10% by weight.An antifoaming agent such as dimethyl silicone oil or methylphenylsilicone oil is added to the composition to prevent foaming. A desirableratio of the antifoaming agent is 1 ppm or more for obtaining theadvantage thereof, and is 1,000 ppm or less for preventing defectiveindication. A more desirable ratio thereof is in the range from 1 ppm to500 ppm.

A polymerizable compound is mixed with the composition to suit for adevice of a polymer sustained alignment (PSA) mode. Preferred examplesof the polymerizable compound include a compound having a polymerizablegroup, such as acrylate, methacrylate, vinyl compounds, vinyloxycompounds, propenyl ether, epoxy compounds (oxirane, oxetane), and vinylketone. An especially desirable example is a derivative of acrylate ormethacrylate. A desirable ratio of the polymerizable compound is 0.05%by weight or more for obtaining the advantage thereof, and is 10% byweight or less for preventing defective displaying. A more desirableratio thereof is in the range from 0.1% to 2% by weight. Thepolymerizable compound is desirably polymerized by UV irradiation and soforth in the presence of a suitable initiator such as aphoto-polymerization initiator. Suitable conditions for thepolymerization, a suitable type of initiators and suitable amounts areknown to those skilled in the art, and are described in the literature.For example, Irgacure 651 (registered trademark), Irgacure 184(registered trademark) or Darocure 1173 (registered trademark) (CibaGeigy AG) that are photo-polymerization initiators are suitable forradical polymerization. The polymerizable compound desirably contains aphoto-polymerization initiator in the range of 0.1% to 5% by weight. Thepolymerizable compound contains especially desirably aphotopolymerization initiator in the range of 1% to 3% by weight.

Seventh, the methods for preparing the component compounds will beexplained. These compounds can be prepared by known methods. The methodsfor the preparation will be exemplified below. The compounds (1-2-1),(4-11-1) and (4-17-1) are prepared by the method disclosed in JPH10-251186 A (1998). The compounds (4-5-1) and (4-8-1) are prepared bythe method disclosed in JP H2-233626 A (1990). The compounds (2-1-1) and(2-4-1) are prepared by the method disclosed in JP H4-30382 B (1992).Antioxidants are commercially available. The compound of formula (6)wherein n is 1 is commercially available from Sigma-Aldrich Corporation.The compound (6) wherein n is 7 is prepared according to the methoddescribed in U.S. Pat. No. 3,660,505 (1972).

The compounds for which preparation methods were not described above canbe prepared according to the methods described in ORGANIC SYNTHESES(John Wiley & Sons, Inc), ORGANIC REACTIONS (John Wiley & Sons, Inc),COMPREHENSIVE ORGANIC SYNTHESIS (Pergamon Press), NEW EXPERIMENTALCHEMISTRY COURSE (Shin Jikken Kagaku Kouza) (Maruzen, Inc.), and soforth. The composition is prepared according to known methods using thecompounds thus obtained. For example, the component compounds are mixedand dissolved in each other by heating.

Last, use of the composition will be explained. The compositions of theinvention mainly have a minimum temperature of −10° C. or less, amaximum temperature of 70° C. or more, and an optical anisotropy in therange of 0.07 to 0.20. The device containing the composition has a largevoltage holding ratio. The composition is suitable for an AM device. Thecomposition is suitable especially for an AM device of a transmissiontype. The composition having an optical anisotropy in the range of 0.08to 0.25 and further the composition having an optical anisotropy in therange of 0.10 to 0.30 may be prepared by controlling the ratios of thecomponent compounds or by mixing with other liquid crystal compounds.The composition can be used as a composition having a nematic phase andas an optically active composition by adding an optically activecompound.

The composition can be used for an AM device. It can also be used for aPM device. The composition can also be used for an AM device and a PMdevice having a mode such as PC, TN, STN, ECB, OCB, IPS, VA, and PSA. Itis especially desirable to use the composition for an AM device having amode of TN, OCB or IPS. These devices may be of a reflection type, atransmission type or a semi-transmission type. It is desirable to usethe composition for a device of a transmission type. It can also be usedfor an amorphous silicon-TFT device or a polycrystal silicon-TFT device.The composition is also usable for a nematic curvilinear aligned phase(NCAP) device prepared by microcapsulating the composition, and for apolymer dispersed (PD) device in which a three-dimensional net-workpolymer is formed in the composition.

EXAMPLES

When a sample was a composition, it was measured as it was, and theobtained value is described here. When a sample was a compound, a samplefor measurement was prepared by mixing 15% by weight of the compound and85% by weight of mother liquid crystals. A value of characteristic ofthe compound was calculated by extrapolating from a value obtained bymeasurement. That is: extrapolated value=(value measured−0.85×value formother liquid crystals)/0.15. When a smectic phase (or crystals)separated out at this ratio at 25° C., a ratio of the compound to motherliquid crystals was changed step by step in the order of (10% byweight/90% by weight), (5% by weight/95% by weight) and (1% byweight/99% by weight), respectively. Values for a maximum temperature,optical anisotropy, viscosity, and dielectric anisotropy of the compoundwere obtained by the extrapolation.

The component of the mother liquid crystals is as shown below. The ratioof the component is expressed by weight %.

Measurement of the characteristics was carried out according to thefollowing methods. Most methods are described in the Standard ofElectronic Industries Association of Japan, EIAJ•ED-2521A or those withsome modifications.

Maximum. Temperature of a Nematic Phase (NI; ° C.): A sample was placedon a hot plate in a melting point apparatus equipped with a polarizingmicroscope and was heated at the rate of 1° C. per minute. A temperaturewas measured when part of the sample began to change from a nematicphase into an isotropic liquid. A higher limit of a temperature range ofa nematic phase may be abbreviated to “a maximum temperature.”

Minimum Temperature of a Nematic Phase (Tc; ° C.): A sample having anematic phase was put in a glass vial and then kept in a freezer attemperatures of 0° C., −10° C., −20° C., −30° C., and −40° C. for tendays, respectively, and a liquid crystal phase was observed. Forexample, when the sample remained in a nematic phase at −20° C. andchanged to crystals or a smectic phase at −30° C., Tc was expressed as≦−20° C. A lower limit of a temperature range of a nematic phase may beabbreviated to “a minimum temperature.”

Viscosity (η; measured at 20° C.; mPa·s): Viscosity was measured bymeans of an E-type viscometer.

Rotation Viscosity (γ1; measured at 25° C.; mPa·s): Rotation viscositywas measured according to the method disclosed in M. Imai, et al.,Molecular Crystals and Liquid Crystals, Vol. 259, p. 37 (1995). A samplewas placed in a TN device, in which a twist angle was 0°, and the cellgap between two glass plates was 5 μm. The TN device was impressed witha voltage in the range of from 16 V to 19.5 V stepwise by 0.5 V. After aperiod of 0.2 second with no impress of voltage, voltage impress wasrepeated with only one rectangular wave (rectangular pulse of 0.2second) and application of no voltage (2 seconds). A peak current and apeak time of a transient current generated by the voltage impress weremeasured. The rotation viscosity was obtained from the measured valuesand the calculating equation (8) in the article presented by M. Imai, etal., p. 40. As for the dielectric anisotropy necessary for thecalculation, the value measured by the measuring method of dielectricanisotropy described below with the device for measuring the rotationviscosity was used.

Optical Anisotropy (Δn; measured at 25° C.): Measurement was carried outwith an Abbe refractometer mounting a polarizing plate on an ocularusing light at a wavelength of 589 nm. The surface of a main prism wasrubbed in one direction, and then a sample was dropped on the mainprism. A refractive index (n∥) was measured when the direction ofpolarized light was parallel to that of the rubbing. A refractive index(n⊥) was measured when the direction of polarized light wasperpendicular to that of the rubbing. A value of optical anisotropy wascalculated from the equation: Δn=n∥−n⊥.

Dielectric Anisotropy (Δε; measured at 25° C.): A sample having anematic phase was put in a TN device having a distance between two glassplates (cell gap) of 9 μm and a twist angle of 80°. Sine waves (10 V, 1kHz) were impressed onto the device, and a dielectric constant (ε∥) in amajor axis direction of a liquid crystal molecule was measured after 2seconds. Sine waves (0.5 V, 1 kHz) were impressed onto the device and adielectric constant (ε⊥) in a minor axis direction of a liquid crystalmolecule was measured after 2 seconds. A value of a dielectricanisotropy was calculated from the equation: Δε=ε∥−ε⊥.

Threshold Voltage (Vth; measured at 25° C.; V): Measurement was carriedout with an LCD Evaluation System Model LCD-5100 made by OtsukaElectronics Co., Ltd. The light source was a halogen lamp. A sample waspoured into a TN device of a normally white mode, in which the cell gapbetween two glass plates was 0.45/Δn (μm), and a twist angle was 80°.Voltage to be impressed onto the device (32 Hz, rectangular waves) wasstepwise increased by 0.02 volt starting from 0 V up to 10 V. During thestepwise increasing, the device was irradiated with light in aperpendicular direction, and the amount of light passing through thedevice was measured. A voltage-transmission curve was prepared, in whicha maximum amount of light corresponded to 100% transmittance and aminimum amount of light corresponded to 0% transmittance. Thresholdvoltage was a value at 90% transmittance.

Voltage Holding Ratio (VHR-1; measured at 25° C.; %): A TN device usedfor measurement had a polyimide-alignment film and the cell gap betweentwo glass plates was 5 μm. A sample was poured into the device, and thenthe device was sealed with an adhesive polymerizable by the irradiationof ultraviolet light. The TN device was impressed and charged with pulsevoltage (60 microseconds at 5 V). Decreasing voltage was measured for16.7 milliseconds with a High Speed Voltmeter and the area A between avoltage curve and a horizontal axis in a unit cycle was obtained. Thearea B was an area without decreasing. The voltage holding ratio is apercentage of the area A to the area B.

Voltage Holding Ratio (VHR-2; measured at 80° C.; %): A TN device usedfor measurement had a polyimide-alignment film and the cell gap betweentwo glass plates was 5 μm. A sample was poured into the device, and thenthe device was sealed with an adhesive polymerizable by the irradiationof ultraviolet light. The TN device was impressed and charged with pulsevoltage (60 microseconds at 5V). Decreasing voltage was measured for16.7 milliseconds with a High Speed Voltmeter and the area A between avoltage curve and a horizontal axis in a unit cycle was obtained. Thearea B was an area without decreasing. The voltage holding ratio is apercentage of the area A to the area B.

Voltage Holding Ratio (VHR-3; measured at 25° C.; %): A voltage holdingratio was measured after irradiating with ultraviolet light to evaluatestability to ultraviolet light. A composition having a large VHR-3 has alarge stability to ultraviolet light. A TN device used for measurementhad a polyimide-alignment film and the cell gap was 5 μm. A sample waspoured into the device, and then the device was irradiated with lightfor 20 minutes. The light source was a super-high pressure mercury lampUSH-500D (made by Ushio, Inc.), and the distance between the device andthe light source was 20 cm. In measurement of VHR-3, decreasing voltagewas measured for 16.7 milliseconds. The VHR-3 is desirably 90% or more,and more desirably 95% or more.

Voltage Holding Ratio (VHR-4; measured at 25° C.; %): A voltage holdingratio was measured after heating a TN device having a sample pouredtherein in a constant-temperature chamber at 80° C. for 500 hours toevaluate stability to heat. A composition having a large VHR-4 has alarge stability to heat. In measurement of VHR-4, decreasing voltage wasmeasured for 16.7 milliseconds.

Response Time (T; measured at 25° C.; millisecond): Measurement wascarried out with an LCD Evaluation System Model LCD-5100 made by OtsukaElectronics Co., Ltd. The light source was a halogen lamp. The low-passfilter was set at 5 kHz. A sample was poured into a TN device of anormally white mode, in which the cell gap between two glass plates was5.0 μm, and a twist angle was 80°. Rectangular waves (60 Hz, 5 V, 0.5second) were impressed to the device. During impressing, the device wasirradiated with light in a perpendicular direction, and the amount oflight passing through the device was measured. A maximum amount of lightcorresponds to 100% transmittance, and a minimum amount of lightcorresponds to 0% transmittance. Rise time (Tr; millisecond) is the timerequired for a change in transmittance from 90% to 10%. Fall time (τf;millisecond) is the time required for a change in transmittance from 10%to 90%. Response time is the sum of the rise time and the fall time thusobtained.

Specific Resistance (p; measured at 25° C.; Ωcm): A sample of 1.0 ml waspoured into a vessel equipped with electrodes. The vessel was impressedwith DC voltage (10 V) and a direct current was measured after 10seconds. Specific resistance was calculated from the following equation:Specific resistance=(voltage×electric capacitance of vessel)/(directcurrent×dielectric constant in a vacuum).

Gas Chromatographic Analysis: A Gas Chromatograph Model GC-14B made byShimadzu Corporation was used for measurement. The carrier gas washelium (2 ml per minute). An evaporator and a detector (FID) were set upat 280° C. and 300° C., respectively. A capillary column DB-1 (length 30m, bore 0.32 mm, film thickness 0.25 μm; dimethylpolysiloxane asstationary phase, no polarity) made by Agilent Technologies, Inc. wasused for the separation of the component compound. After the column hadbeen kept at 200° C. for 2 minutes, it was further heated to 280° C. atthe rate of 5° C. per minute. A sample was prepared in an acetonesolution (0.1% by weight), and 1 μl of the solution was injected intothe evaporator. A recorder used was a Chromatopac Model C-R5A made byShimadzu Corporation or its equivalent. A gas chromatogram obtainedshowed the retention time of a peak and a peak area corresponding to thecomponent compound.

Solvents for diluting the sample may also be chloroform, hexane, and soforth. The following capillary column may also be used: HP-1 made byAgilent Technologies, Inc. (length 30 m, bore 0.32 mm, film thickness0.25 μm), Rtx-1 made by Restek Corporation (length 30 m, bore 0.32 mm,film thickness 0.25 μm), and BP-1 made by SGE International Pty. Ltd.(length 30 m, bore 0.32 mm, film thickness 0.25 μm). In order to preventcompound peaks from overlapping, a capillary column CBP1-M50-025 (length50 m, bore 0.25 mm, film thickness 0.25 μm) made by Shimadzu Corporationmay be used.

The ratio of liquid crystal compounds contained in the composition maybe calculated by the following method. The liquid crystal compounds canbe detected with a gas chromatograph. The area ratio of each peak in thegas chromatogram corresponds to the ratio (number of moles) of liquidcrystal compounds. When the above capillary columns are used, thecorrection coefficient of each liquid crystal compound may be regardedas 1. Therefore, the ratio of liquid crystal compounds (% by weight) iscalculated from the area ratio of each peak.

The invention will be explained in detail by way of Examples. Theinvention is not limited by the Examples described below. The compoundsdescribed in Comparative Examples and the Examples are expressed by thesymbols according to the definition in Table 3. In Table 3, theconfiguration of 1,4-cyclohexylene is trans. The parenthesized numbersnext to the symbolized compounds in the Examples correspond to thenumbers of the desirable compounds. The symbol (—) means other liquidcrystal compound. The ratios (percentage) of liquid crystal compoundsare expressed by percentage by weight (% by weight) based on the totalweight of liquid crystal compositions, and the liquid crystalcompositions contain impurities in addition to the liquid crystalcompounds. Last, the characteristics of the compositions are summarized.

TABLE 3 Method of Description of Compound using Symbols R—(A₁)—Z₁— . . .—Z_(n)—(A_(n))—R′ 1) Left Terminal Group R— Symbol C_(n)H2_(n+1)— n-C_(n)H_(2n+1)O— nO— C_(m)H2_(m+1)OC_(n)H_(2n)— mOn- CH₂═CH— V—C_(n)H_(2n+1)—CH═CH— nV— CH₂═CH—C_(n)H_(2n)— Vn-C_(m)H_(2m+1)—CH═CH—C_(n)H_(2n)— mVn- CF₂═CH— VFF— CF₂═CH—C_(n)H_(2n)—VFFn- 2) Right Terminal Group —R′ Symbol —C_(n)H_(2n+1) -n —OC_(n)H₂₊₁—On —CH═CH₂ —V —CH═CH—C_(n)H_(2n+1) —Vn —C_(n)H_(2n)—CH═CH₂ -nV —CH═CF₂—VFF —F —F —Cl —CL —OCF₃ —OCF3 3) Biding Group —Z_(n)—

—C₂H₄— 2 —COO— E —CH═CH— V —C≡C— T —CF₂O— X 4) Ring Structure —A_(n)—Symbol

H

B

B(F)

B(2F)

B(F,F)

B(2F,5F)

Py

G 5) Example of Description Example 1 V2-BB(F)B-1

Example 2 3-HB—CL

Example 3 1O1-HBBH-5

Example 4 3-BB(F,F)XB(F)—OCF3

Comparative Example 1

Example 39 was selected from among compositions disclosed in WO1966-011897 A. The basis for the selection was because the compositioncontained the compound (4) and had the highest maximum temperature andthe largest optical anisotropy. The composition had the followingcomponents and characteristics.

3-HBXB(F,F)-F (4) 3% 5-HBXB(F,F)-F (4) 8% 3-HBXB-OCF3 (4) 5% 2-HBB(F)-F(4) 8% 3-HBB(F)-F (4) 8% 5-HBB(F)-F (4) 16% 5-HB-F (4) 6% 7-HB-F (4) 6%5-HHB-OCF3 (4) 8% 3-H2HB-OCF3 (4) 8% 5-H2HB-OCF3 (4) 8% 3-HH2B-OCF3 (4)8% 5-HH2B-OCF3 (4) 8% NI = 84.9° C.; Δn = 0.101; Δε = 5.5; Vth = 2.12V;η = 16.6 mPa · s.

Comparative Example 2

Example 1 was selected from among compositions disclosed in JP2003-176251 A. The basis for the selection was because the compositioncontained the compounds (3-3-1), (4) and (4-6), and had the highestmaximum temperature and the largest optical anisotropy. The compositionhad the following components and characteristics.

3-HHB(F)-F (4) 10.8% 5-HHB(F)-F (4) 9% 3-HH2B-OCF3 (4) 4.5% 5-HH2B-OCF3(4) 4.5% 3-HB(F)BH-3 (3-3-1) 1.8% 5-HB(F)BH-3 (3-3-1) 1.8% 5-HB(F)BH-5(3-3-1) 1.8% 6-HB-F (4) 7.2% 7-HB-F (4) 5.4% 2-HHB-OCF3 (4) 7.2%3-HHB-OCF3 (4) 10.8% 4-HHB-OCF3 (4) 6.3% 5-HHB-OCF3 (4) 9.9% 5-HB-F (4)9% V-HHXB(F,F)-F (4-6) 10% NI = 90.3° C.; Δn = 0.095; Δε = 5.6.

Example 1

It was found that the composition of Example 1 had a higher maximumtemperature and a larger optical anisotropy than those of ComparativeExample 1.

5-HBB(F)B(F,F)XB(F,F)-F (1-1-1-1) 10% V-HH-3 (2-1-1) 37% 1V-HH-3 (2-1-1)11% V-HHB-1 (2-4-1) 11% V2-HHB-1 (2-4-1) 3% 2-BB(F)B-3 (2-6-1) 8%5-HBB(F)B-2 (3-4-1) 4% 3-HBB(F,F)-F (4-8-1) 6% 4-BB(F)B(F,F)XB(F,F)-F(4-17-1) 10% NI = 97.9° C.; Tc ≦ −30° C.; Δn = 0.119; Δε = 4.6; Vth =2.5l V; η = 17.2 mPa · s; VHR-1 = 99.1%; VHR-2 = 98.2%; VHR-3 = 98.1%.

Example 2

It was found that the composition of Example 2 had a higher maximumtemperature and a larger optical anisotropy than those of ComparativeExample 2.

5-HHB(F)B(F,F)XB(F,F)-F (1-2-1-1) 5% 5-HHB(F,F)XB(F)B(F,F)-F (1-2-2-1)5% V-HH-4 (2-1-1) 20% V-HH-5 (2-1-1) 10% 1V-HH-3 (2-1-1) 11% V-HHB-1(2-4-1) 5% 5-HBB(F)B-2 (3-4-1) 6% 5-HBB(F)B-3 (3-4-1) 6% 5-HB-CL (4-1-1)5% 3-HHXB(F,F)-F (4-6-1) 5% 3-HBB-F (4-7-1) 6% 3-BB(F,F)XB(F,F)-F(4-11-1) 6% 3-HHBB(F,F)-F (4-13-1) 5% 4-HHBB(F,F)-F (4-13-1) 5% NI =109.0° C.; Tc ≦ −40° C.; Δn = 0.118; Δε = 4.5; Vth = 2.77 V; η = 25.6mPa · s; VHR-1 = 99.2%; VHR-2 = 98.3%; VHR-3 = 98.2%.

Example 3

It was found that the composition of Example 3 had a higher maximumtemperature and a larger optical anisotropy than those of ComparativeExample 1.

5-HB(F)B(F)B(F,F)XB(F,F)-F (1-1-1-2) 5% 5-HB(F)B(F,F)B(F,F)XB(F,F)-F(1-1-1-3) 5% V-HH-3 (2-1-1) 36% 1-BB(F)B-2V (2-6-1) 6% 2-BB(F)B-2V(2-6-1) 6% 3-BB(F)B-2V (2-6-1) 11% 1O1-HBBH-5 (—) 5% 3-HHB-CL (4-4-1) 5%3-BB(F,F)XB(F,F)-F (4-11-1) 11% 4-BB(F)B(F,F)XB(F,F)-F (4-17-1) 10% NI =96.7° C.; Tc ≦ −30° C.; Δn = 0.147; Δε = 8.1; Vth = 1.85 V; η = 30.6 mPa· s; VHR-1 = 99.2%; VHR-2 = 98.3%; VHR-3 = 98.2%.

Example 4

It was found that the composition of Example 4 had a higher maximumtemperature and a larger optical anisotropy than those of ComparativeExample 2.

5-HHB(F)B(F,F)XB(F,F)-F (1-2-1-1) 10% 5-HB(F)B(F,F)XB(F)B(F,F)-F(1-1-2-1) 5% V-HH-3 (2-1-1) 36% V-HBB-1 (2-5-1) 10% 3-HHEBH-3 (3-1-1) 5%3-HHEBH-4 (3-1-1) 5% 3-HHEBH-5 (3-1-1) 5% 4-HBB(F,F)XB(F,F)-F (4-15-1)5% 3-HHEB(F,F)-F (4-20) 10% 2-HBEB(F,F)-F (4-21) 3% 3-HBEB(F,F)-F (4-21)3% 5-HBEB(F,F)-F (4-21) 3% NI = 121.1° C.; Tc ≦ −40° C.; Δn = 0.108; Δε= 6.6; Vth = 2.01 V; η = 32.8 mPa · s; VHR-1 = 99.2%; VHR-2 = 98.3%;VHR-3 = 98.2%.

Example 5

5-HHB(F)B(F,F)XB(F,F)-F (1-2-1-1) 5% 5-HHB(F,F)XB(F)B(F,F)-F (1-2-2-1)5% 2-HH-5 (2-1-1) 11% 3-HH-4 (2-1-1) 15% 3-HH-5 (2-1-1) 5% 3-HB-02(2-2-1) 5% 3-HHB-1 (2-4-1) 10% 5-HBB(F)B-2 (3-4-1) 5% 5-HBB(F)B-3(3-4-1) 5% 2-HHB(F,F)-F (4-5-1) 10% 3-HHB(F,F)-F (4-5-1) 10%3-HBB(F,F)-F (4-8-1) 14% NI = 100.7° C.; Tc ≦ −30° C.; Δn = 0.113; Δε =5.2; Vth = 2.21 V; η = 20.4 mPa · s; VHR-1 = 99.1%; VHR-2 = 98.1%; VHR-3= 98.1%.

Example 6

5-HBB(F)B(F,F)XB(F,F)-F (1-1-1-1) 10% V-HH-3 (2-1-1) 35% 1V-HH-3 (2-1-1)10% V-HHB-1 (2-4-1) 10% V2-HHB-1 (2-4-1) 6% 5-HBB(F)B-2 (3-4-1) 5%3-HB-CL (4-1-1) 9% 3-PyBB-F (4-10-1) 5% 4-PyBB-F (4-10-1) 5% 5-PyBB-F(4-10-1) 5% NI = 100.7° C.; Tc ≦ −30° C.; Δn = 0.120; Δε = 3.1; Vth =2.67 V; η = 16.2 mPa · s; VHR-1 = 99.2%; VHR-2 = 98.2%; VHR-3 = 98.2%.

Example 7

5-HHB(F)B(F,F)XB(F,F)-F (1-2-1-1) 10% V-HH-3 (2-1-1) 35% V-HHB-1 (2-4-1)10% 2-HB(F)BH-5 (3-3-1) 5% 3-HB(F)BH-5 (3-3-1) 5% 2-BB(F)B(F,F)-F(4-9-1) 5% 3-BB(F)B(F,F)-F (4-9-1) 5% 4-BB(F)B(F,F)-F (4-9-1) 5%5-BB(F)B(F,F)-F (4-9-1) 5% 3-HHB(F)B(F,F)-F (4-14-1) 5%4-BB(F)B(F,F)XB(F,F)-F (4-17-1) 10% NI = 99.9° C.; Tc ≦ −30° C.; Δn =0.132; Δε = 8.4; Vth = 1.67 V; η = 31.2 mPa · s; VHR-1 = 99.0%; VHR-2 =98.2%; VHR-3 = 98.1%.

Example 8

5-HBB(F)B(F,F)XB(F,F)-F (1-1-1-1) 5% 5-HB(F)B(F,F)XB(F)B(F)-OCF3(1-1-2-2) 5% V-HH-3 (2-1-1) 30% 1V-HH-3 (2-1-1) 5% V-HHB-1 (2-4-1) 5%3-HHEBH-3 (3-1-1) 5% 5-HBB(F)B-2 (3-4-1) 5% 5-HBB(F)B-3 (3-4-1) 5%3-BB(F,F)XB(F)-OCF3 (4-12-1) 5% 2-HGB(F,F)-F (4-22) 2% 3-HGB(F,F)-F(4-22) 3% 4-HGB(F,F)-F (4-22) 3% 5-HGB(F,F)-F (4-22) 2% 4-GHB(F,F)-F(4-23) 5% 5-GHB(F,F)-F (4-23) 15% NI = 100.2° C.; Tc ≦ −30° C.; Δn =0.105; Δε = 7.3; Vth = 1.68 V; η = 29.5 mPa · s; VHR-1 = 99.0%; VHR-2 =98.1%; VHR-3 = 98.2%.

INDUSTRIAL APPLICABILITY

The liquid crystal composition is suitable for use in an active matrix(AM) device and so forth. The liquid crystal composition has a characterof a positive dielectric anisotropy so it is suitable for use a deviceof a twisted nematic (TN) mode, an optically compensated bend (OCB)mode, an in-plane switching (IPS) mode or a polymer sustained alignment(PSA) mode.

1. A liquid crystal composition having a nematic phase that comprisesthree components, wherein a first component is at least one compoundselected from the group of compounds represented by formulas (1-1) and(1-2), a second component is at least one compound selected from thegroup of compounds represented by formula (2), and a third component isat least one compound selected from the group of compounds representedby formula (3):

wherein R¹ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons or alkenyl having 2 to 12 carbons; R² and R³ are eachindependently alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12carbons in which arbitrary hydrogen is replaced by fluorine; ring A,ring B, ring C and ring D are each independently 1,4-cyclohexylene,1,4-phenylene, 2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene, or2,5-difluoro-1,4-phenylene; Z¹, Z² and Z³ are each independently asingle bond, ethylene, carbonyloxy or difluoromethyleneoxy; at least oneof Z¹, Z² and Z³ is difluoromethyleneoxy; Z⁴, Z⁵ and Z⁶ are eachindependently a single bond, ethylene or carbonyloxy; X¹, X², X³, X⁴,X⁵, X⁶, X⁷ and X⁸ are each independently hydrogen or fluorine; Y¹ isfluorine, chlorine or trifluoromethoxy; and m is 0 or
 1. 2. The liquidcrystal composition according to claim 1, wherein the first component isat least one compound selected from the group of compounds representedby formulas (1-1-1) to (1-1-3), (1-2-1) and (1-2-2):

wherein R¹ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons or alkenyl having 2 to 12 carbons; X¹, X², X³, X⁴, X⁵, X⁶, X⁷,and X⁸ are each independently hydrogen or fluorine; and Y¹ is fluorine,chlorine or trifluoromethoxy.
 3. The liquid crystal compositionaccording to claim 2, wherein the first component is at least onecompound selected from the group of compounds represented by formulas(1-1-1) and (1-2-2).
 4. The liquid crystal composition according toclaim 1, wherein the second component is at least one compound selectedfrom the group of compounds represented by formulas (2-1) to (2-6).

wherein R² and R³ are each independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, oralkenyl having 2 to 12 carbons in which arbitrary hydrogen is replacedby fluorine.
 5. The liquid crystal composition according to claim 4,wherein the second component is at least one compound selected from thegroup of compounds represented by formula (2-1).
 6. The liquid crystalcomposition according to claim 4, wherein the second component is atleast one compound selected from the group of compounds represented byformula (2-6).
 7. The liquid crystal composition according to claim 4,wherein the second component is a mixture of at least one compoundselected from the group of compounds represented by formula (2-1), andat least one compound selected from the group of compounds representedby formula (2-4).
 8. The liquid crystal composition according to claim4, wherein the second component is a mixture of at least one compoundselected from the group of compounds represented by formula (2-1), andat least one compound selected from the group of compounds representedby formula (2-6).
 9. The liquid crystal composition according to claim4, wherein the second component is a mixture of at least one compoundselected from the group of compounds represented by formula (2-1), atleast one compound selected from the group of compounds represented byformula (2-4), and at least one compound selected from the group ofcompounds represented by formula (2-6).
 10. The liquid crystalcomposition according to claim 1, wherein the third component is atleast one compound selected from the group of compounds represented byformulas (3-1) to (3-4):

wherein R² and R³ are each independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, oralkenyl having 2 to 12 carbons in which arbitrary hydrogen is replacedby fluorine.
 11. The liquid crystal composition according to claim 10,wherein the third component is at least one compound selected from thegroup of compounds represented by formula (3-4).
 12. The liquid crystalcomposition according to claim 1, wherein the ratio of the firstcomponent is in the range of 5% to 25% by weight, the ratio of thesecond component is in the range of 30% to 80% by weight, and the ratioof the third component is in the range of 5% to 25% by weight, based onthe total weight of the liquid crystal composition.
 13. The liquidcrystal composition according to claim 1, wherein the compositionfurther includes at least one compound selected from the group ofcompounds represented by formula (4) as the fourth component.

wherein R¹ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons or alkenyl having 2 to 12 carbons; ring E is independently1,4-cyclohexylene, 1,3-dioxane-2,5-diyl, 1,4-phenylene,3-fluoro-1,4-phenylene, 3,5-difluoro-1,4-phenylene, or 2,5-pyrimidine;Z¹ is independently a single bond, ethylene, carbonyloxy, ordifluoromethyleneoxy; X¹ and X² are each independently hydrogen orfluorine; Y¹ is fluorine, chlorine or trifluoromethoxy; and n is 1, 2 or3.
 14. The liquid crystal composition according to claim 13, wherein thefourth component is at least one compound selected from the group ofcompounds represented by formulas (4-1) to (4-17):

wherein R⁴ is alkyl having 1 to 12 carbons, or alkenyl having 2 to 12carbons.
 15. The liquid crystal composition according to claim 14,wherein the fourth component is at least one compound selected from thegroup of compounds represented by formula (4-9). 16-21. (canceled) 22.The liquid crystal composition according to claim 13, wherein the ratioof the first component is in the range of 5% to 25% by weight, the ratioof the second component is in the range of 30% to 80% by weight, and theratio of the third component is in the range of 5% to 25% by weight, andthe ratio of the fourth component is in the range of 5% to 45%, based onthe total weight of the liquid crystal composition.
 23. The liquidcrystal composition according to claim 1, wherein the composition has amaximum temperature of a nematic phase of 70° C. or more, an opticalanisotropy (25° C.) at a wavelength of 589 nm of 0.08 or more, and adielectric anisotropy (25° C.) at a frequency of 1 kHz of 2 or more. 24.A liquid crystal display device containing the liquid crystalcomposition according to claim
 1. 25. The liquid crystal display deviceaccording to claim 24, wherein the operation mode of the liquid crystaldisplay device is a twisted nematic (TN) mode, an optically compensatedbend (OCB) mode, or an in-plane switching (IPS) mode, and the drivingmode of the liquid crystal display device is an active matrix mode. 26.The liquid crystal display device according to claim 25, wherein theoperation mode of the liquid crystal display device is a polymersustained alignment (PSA) mode, and the driving mode of the liquidcrystal display device is an active matrix mode.